Technical Field
The invention relates generally to a light emitting module, and more particularly to a light emitting module using a light emitting diode chip as the light source.
Related Art
A light emitting diode (LED) is a light emitting element constituted by a semiconductor material having group III-V elements. The LED has advantages such as long service life, small volume, high shock resistance, low heat output, and low power consumption. Thus, it has been widely utilized in indicators or light sources for household appliances and various instruments. In recent years, the LED has been developed towards multicolor and high brightness; therefore, its application scope has been expanded to large outdoor display boards, traffic signal lights, and the like. In the future, the LED may even become the main illumination light source with both power-saving and environment-protecting functions.
In the designs of conventional LED modules, the light beam emitted by the LED chip is projected directly. In other words, the light beam generated by the LED chip has high directivity, and thus may result in unfavorable light uniformity and glares that would cause discomfort for the user. Moreover, in order to generate the white LED light source, typically a plurality of LED chips of different colors (e.g., red, blue, and green) with the same size are configured in an array on the carrier for packaging. However, as the light from these LEDs is emitted forward directly, a large light mixing area is needed to harmonize the light. The size of the whole LED module is increased as a consequence, which causes inconvenience.
To resolve the aforementioned problems, an optical lens is usually configured in the current LED modules, so that the light beam emitted by the LED chips can be utilized effectively. However, when the LED chips are covered by the optical lens, due to light of different color having different refraction angles with the optical lens, the illumination angle generated by the whole LED illumination module may be too small or focused at a certain region. For example, a part of the red light appears at a specific range, such that the distribution of chroma for the entire illumination regions becomes irregular, and thereby the LED module may have problems such as non-uniform light or low color render index of the light source.